Cam pawl actuator

ABSTRACT

A rifle bar rotation mechanism for a pneumatic drill wherein remote control of rotation modes is accomplished by rotation of a cam element to control the engagement of pawl elements with a toothed ratchet member.

[ Aug. 13, 1974 United States Patent [191 Le Blane CAM PAWL ACTUATOR [76] Inventor: Louis H. Le Blanc, Glenwood Primary ExammerT'Samue] Scott Rd., Claremont, NH. 03743 Jan. 8, 1973 Appl. No.: 321,795

Assistant Examiner-Wesley S. Ratliff, Jr.

[22] Filed:

ABSTRACT A rifle bar rotation mechanism for a pneumatic drill wherein remote control of rotation modes is accom- [52] US. 74/127, l73/96 g l' 'lilf f g g g plished by rotation of a cam element to control the en- [56] References Cited I UNITED STATES PATENTS gagement of pawl elements with a toothed ratchet member.

' Claims, 5 Drawing Figures 3,143,931 8/1964 Worman 74/127 PATENTED AUG I 31974 SHEET 1 [IF 3 FIG.

PATENTED nus: 3mm

3;aaa'.s17

I sum 3 or 3 FIG 5 1 CAMPAWL ACTUATOR In the field of rock drilling the use of rifle bar rotation to provide drill steel rotation during percussive action of a hammer piston by the use of a rifle bar and ratchet mechanism to provide remote control of the three desired modes of rotation namely; forward, neutral, or reverse rotation, as desired, is well known. Apparatus operating in such a manner has'in the past been applied in rock drills by the use of rotatably movable ring shaped control elements engagable with oppositely effective pawl elements by rotation of the control rings forwardly for one mode of operation and rearwardly for another mode of operation in response to the action of fluid operated mechanisms of relatively complicated structure occupying a relatively large space within the rock drill.

Such devices have served the purpose but are very I difficult if not impossible to incorporate in smaller sized drills with the result that remote control of rifle bar rotation in such drills has been relatively expensive and unreliable or not even offered as compared to that for larger drills.

The present invention provides for pawl engagement control by the use of an outwardly acting cam element activated by simple rotation of the cam into one of three different positions for the desired rotation modes. The cam element of this invention is directly rotatable, by rack and pinion operation of a piston directly engaged therewith so that compared to earlier apparatus fewer parts are used-and the size of the actuating mechanism is substantially reduced from that above described. Because of the relatively small assembled size and lesser number of parts the cam pawl actuator of this invention is relatively inexpensive and relatively more reliable than those of prior art apparatus.

These and other advantages and objects of this invention will be more readily apparent upon consideration of the following description and drawings in which:

FIG. 1 is a sectional view taken substantially on line 11 of FIG. 2, looking in the direction indicated by the arrows, of the body of a rock drill constructed according to the principles of this invention;

FIG. 2 is a side elevational fragmentary view of the rock drill of FIG. 1 with a sectional portion taken substantially on line 22 of FIG. 1 looking in the direction indicated by the arrows;

FIG. 3 is a partially schematic partially sectional view of a rock drill of FIG. 1 showing the cam pawl actuator of this invention as found in the apparatus of FIG. 1 with a cam element in neutral position;

FIG. 4 is a partially schematic representation similar to FIG. 3 but showing the cam element in position to provide for clockwise rotation of a drill steel;

FIG. 5 is another representation similar to FIG. 3 with the cam element in position to provide for counter clockwise rotation of a drill steel actuated by the rock drill of this invention;

The hammer rock drill in which the present invention is employed may be of a conventional design generally like that described in US. Pat. No. 3,044,448 (Curtis) wherein drill rotation is provided by rifle bar action wherein forward motion of the hammer piston to strike a blow on the drill steel will tend to rotate the rifle bar in a particular direction while backward motion of the hammer piston away from the drill steel will tend to rotate the rifle bar in the opposite direction. The latter rotation being prevented by a ratchet mechanism, the piston will be rotated in the first direction as is well known.

Referring now to FIG. 2, there is shown a portion of a hammer rock drill generally indicated at 10 having an elongated body member comprising a cylinder member 12 partially shown extending to the right of FIG. 2 which encloses and supports for reciprocation therein a piston (not shown) for hammer actuation of drill steels and a drill bit in a well known manner. The cylinder member 12 is provided with an axially extending stepped cylindrical bore, a small portion of which is shown at 14 in FIG. 2. Within this portion 14 of the bore is mounted a ratchet pawl mounting ring 16 extending leftwardly from the body member 12 as seen in FIG. 2 and peripherally encompassed and secured in position by another portion of the body member a rock drill backhead generally indicated at 18, constructed according to the principles of this invention.

Within the backhead 18 there is a cross bore 20 extending all the way across the backhead as seen in FIG. 1 being plugged at one end with a common closure element such as a pipe plug 22 and provided at the other end, to the right as seen in FIG. 1, with a tubular member 21 secured within a threaded end of the cross bore 20 in fluid tight engagement therewith in a well known manner. A forward leading passageway 24 provides for the supply of compressed air for running rock drill of this invention from the tubular member 21 connected to a supply of such compressed air (not shown) to the bore 20 and through the passageway 24 and a suitable opening 26 in the mounting ring 16 through valve means (not shown) into the cylinder of the rock drill 10 in a well known manner.

Extending through the backhead 18 from rear to front (left to right as seen in FIG. 2) is a cylindrical bore 28 coaxial with the stepped cylindrical bore 14 of the cylinder member 12. Rotatably mounted in fluid tight relationship with the bore 28 and extending therethrough is a cam member 30 having a generally cylindrical central body portion 31, an enlarged head portion 32, within the forward end of backhead 18 (to the right as seen in FIG. 2) and a toothed portion. 33 extending along the rearward or left hand portion as seen in FIG. 2 for a purpose to be described. Within the cam member 30 there is an axial throughbore 34 having at.

its left hand end a threaded portion 35 and at its right hand end as seen in FIG. 2 a shoulder portion 36 against which is mounted suitable packing 39 upon which is seated the head portion of a centrally extending blow tube 38 of a well known design extending from the right hand portion of the back head 18 through the center of the cylinder member 12 to communicate with drill steel and drill bit central bores as is known.

Threadedly engaged within the threads 35 of the bore 34 is a retainer member abuttingly engaged with the head portion of the blow tube 38 to maintain the sealed effect of the head portion of the blow tube 38 against the packing 39 and the shoulder 36 of the bore 34. The retainer 40 has a head portion to the left shown as hexagonaland in this particular embodiment is a generally solid member down to a cross bored portion having openings 41 immediately adjacent the head of the blow tube 38 for a purpose to be made plain. The cam member 30 is provided with a peripheral groove 42 encircling the cam member 30 and cross bores 43 through the member 30 bringing groove 42 into communication with openings 41 in the right hand end of the retainer 40. The groove 42 in turn communicates by way of passageway 44 with a source of blow air or cleansing water (not shown) for the purpose of cleaning chips out of the .hole formed by the action of the rock drill of this invention in a well known manner.

In other modifications of this device (not shown) the retainer 40 is made hollow and the blow air or water is furnished axially therethrough rather than from side passageways such as 44.

Extending crosswise of the back head 18 parallel to the bore and near the bottom of the back head 18 as seen in FIG. 1 is a cross bore 50 having a smooth cylindrical central portion and threaded end portions at each side of the back head 18. Within each end of the 68, of a well known type, the teeth of which are seen bore 50 is threadedly mounted in fluid tight relationtion of a spring support pin 54 secured in the internal 7 bore 53 of each of the stop members 52 for receiving and supporting the inactive end of prestressed spring member 56 of the compression type secured on the pin 54 by way of a washer 57 and some kind of retaining means such as a snap ring or the like. The washers 57 biased inwardly toward the center of the back head 18 by the springs 56 are in contact with the interior of a pair of blind bores 58 extending inwardly of a cylindrical piston member 60 slidably mounted within the bore 50 and held centrally of the axial dimension of the bore 50 by the spring members 56 in a known manner. Between the inner ends of the stop members 52 and the adjacent ends of the piston member 60 are right and left spaces 46 and 47, respectively, shown to be equal in FIG. 3.

There is shown connected to the outer end of the right hand stop member 52 a pipe connection elbow 62 through which air under pressure can be supplied, from a remote source (not shown) to the space 46 at the right hand end of the piston member 60 within the bore 50. Another such connection (not shown) connects by way of passageways partially shown at 63 to the space 47 between the left hand end of the piston 60 and the inner end of the left hand bushing member 52 so that when air is supplied to the tube 62 and passageway 63 is connected to atmosphere the piston 60 will move to the left while with the connection 62 connected to atmosphere and its companion connection from passageway 63 connected 'to air pressure the piston 60 will be moved to the right in a well known manner. The central portion of the piston '60 is provided with gear teeth in rack formation in toothed engagement with the toothed portion 33 of the cam member as best seen in FIGS. 1, 3, 4, and 5. It is obvious when the piston 60 moves back and forth the cam member 30 will be rotated as hereinafter more fully explained.

As best seen in FIGS. 3, 4 and 5 the head portion 32 of the cam member 30 is provided with a plurality of arcuate notches 66 shown as four equally spaced notches at 90 from each other leaving a full diameter head portion between each pair of notches for a purpose to be described.

As best seen in FIG. 2 the mounting ring 16 surrounds the head portion 32 of the cam member 30 and also surrounds the ratchet toothed head of a rifle bar FIGS. 3, 4 and 5 mostly in phantom and identified as tooth elements 70. Mounted within the ring 16 and pivotable therein is a plurality of spring biased pawls 72 pointing counter clockwise and 73 pointing clockwise. In this particular embodiment there are four of pawls 72 and only two of pawls 73 because the pawls 72 are for providing forward rotation during the working mode while the pawls 73 provide reverse rotation during withdrawal or unscrewing of the drill steels.

These pawls 72 and 73 have an axial width extending the full length of the teeth and part of the thickness of the head portion 32 so that when no notch is present under the free end of a pawl member 72 or 73 that member is held up out of engagement with the teeth 70 which are of the same or slightly smaller diameter than the full diameter of the head portion 32 between notches. 7

As seen in FIG. 3 with the piston 60 in its central location the full diameter portions of the head portion 32 are engaged with and holding all of the pawls 72 and 73 in the disengaged mode so that even with the hammer running back and forth the drill steel will not be rotated since the rifle bar 68 is free to rotate back and forth as the piston passes over it.

When compressed air or other pressure fluid is admitted to the left hand end 47 of the bore 50 the piston 60 as seen in FIG. 4 will be moved to the right rotating the head portion 32 in a counterclockwise direction until the pawls 73 are free of the full diameter portions of the head portion 32 and able to drop into engagement with the teeth 70 of the rifle bar 60 so that when the piston moves forward the rifle bar cannot turn in the counterclockwise direction so the piston with its associated rotating parts must turn in the clockwise direction as viewed from the back end of the drill which would be the correct direction for disengaging left hand threaded drill-steels for which this particular embodiment is designed. When the piston returns toward the back head 18 the rifle bar will be urged in the clockwise direction and free to move with the pawls 73 being biased out of the way by contact with the teeth 70 in a well known manner.

When the left hand end 47 of the bore 50 is connected to atmosphere and pressure fluid such as compressed air is supplied to the right hand end 46 of the bore 50 the piston 60 will move to the left as seen in FIG. 5 and the cam member 30 rotated in a clockwise direction as seen in FIG. 5 will provide notches 66 for each of the four pawl members 72 which will thereupon be free to engage the teeth 70 of the rifle bar 68 in such a manner that when the piston is in forward motion along the rifle bar 68 the rifle bar will be free to rotate in the counter clockwise direction because the teeth 70 will bias the pawls 72 out of the way while the pawls 73 are held out of engagement with the teeth 70 by the full diameter portions of the head portion 32. As the piston returns towards the back head 18 it will attempt to turn the ratchet teeth 70 to the right or in a clockwise direction which direction will bring the pawls 72 into contact with the teeth 70 in an abutting manner and the rifle bar 68 will be held from turning forcing the piston and attached parts including the drill steel and drill bit to turn in the counter clockwise direction which is proper for left hand threaded drill steels.

It is also to be noted that the cam member 30 is in toothed engagement with a lever 76 mounted on the rearward end of the cam member 30 and rotatable therewith. The lever 76 is also in contact with a spring biased detent 78 seated in a slight countersink in the lever 76 and protruding from a bore 80 in the back head 18 so that the cam member 30 can be rotated by manual effort in either direction to provide the desired rotation and also so that the piston 60 and spring members 56 and associated parts may beremoved and the entire control of the rifle bar action be made manual with the detent member 78 holding the cam member 30 in the neutral position until a force is applied to the lever 76 to rotate it in the desired direction providing the selected rotation of the piston and associated drilling parts.

Thus it is plain that the cam pawl actuation of this invention can be used with remotely controlled air connections or other pressure fluid connections and it can also be used in the complete manual mode with no piston actuation needed.

The principles of this invention are particularly applied in the use of a cam mechanism working internally upon the pawl elements as described and because of its direct connection from the piston through the pawl elements there is little possibility of failure of any part of this pawl controlling device and the amount of room and the number of parts necessary will be considerably less than with prior art devices. Further advantages resident in the device of this invention arise from the use of a hollow cam member extending axially within the back head into communication with the internal passageway of the blow tube without interfering with the cam action.

A preferred embodiment of this invention having hereinabove been shown and described it is to be realized that variations in the application ofthe principles of this invention are envisioned and expected within the scope of this invention. It is therefore respectfully requested that this invention be interpreted as broadly as possible limited only by the claims appended hereto.

What is claimed is:

1. A rifle bar rotation mechanism for a rock drill comprising: an axially extending elongated body member; an axially extending bore in said body member; an elongated rifle bar having a longitudinally extending bore therethrough and having one end portion thereof rotatably mounted within said body member bore; first means received within said body member bore and cooperable with second means on said one end portion for selectively controlling the rotation of said rifle bar; a hollow cam member rotatably coaxially received within said body member bore; said cam member having a peripheral camming surface thereof for controlling the cooperation of said first and second members; first rotative means being in radial driving engagement with said cam member and adapted to be responsive to pressure fluid supplied thereto to rotate said cam member coaxially with respect to the longitudinal axis of said bore; second rotative means having a portion thereof coaxially aligned with said cam member and in driving engagement therewith; and having at least another portion thereof located externally of said body member and being manually operable to rotate said cam member coaxially with respect to the longitudinal axis of said bore; and said first and second rotative means being selectively operable independently of each other.

. 2. A rifle bar rotation mechanism as specified in claim 1 wherein said body member includes a back head element having therein a rearward portion of said body member bore and said cam member is received within said rearward portion.

3. A rifle bar rotation mechanism as specified in claim 2 wherein said first means comprises a plurality of pawl elements pivotally mounted within said body member bore forwardly of said back head, and said second means comprises ratchet teeth on a head element forming said one end portion of said rifle bar.

4. A rifle bar rotation mechanism as specified in claim 3 wherein said pawl elements are tangentially engagable with said ratchet teeth, some of said pawl elements thus engagable to prevent rotation of said rifle bar in one direction of rotation and at least one other of said pawl elements thus engagable to prevent rotation of said rifle bar in the opposite direction.

5. A rifle bar rotation mechanism as specified in claim 2 wherein said back head has a cross bore therein peripherally intersecting said rearward portion of said body bore and said first rotative means comprises a double acting piston slidably received in said cross bore and engaging said cam member.

6. A rifle bar rotation mechanism as specified in claim 5 wherein end portions of said cross bore are adapted to be in communication with a source of pressure fluid.

7. A rifle bar rotation mechanism as specified in claim 6 wherein said communication of one of said cross bore end portions with a source of pressure fluid is simultaneous with communication of the other of said cross bore end portions with the ambient atmosphere.

8. A rifle bar rotation mechanism as specified in claim 2 wherein said backhead is provided with a passageway providing said adaptation for communication of said interior of said back head with such a source of pressure fluid.

9. A rifle bar rotation mechanism as specified in claim 8 wherein a blow tube is slidably received in said rifle bar bore to provide communication of said cam member interior through said rifle bar bore.

10. A rifle bar rotation mechanism as specified in claim 9 wherein said cam member interior is a through bore therein sealingly receiving a head portion of said blow tube and having a side opening communicating with said back head passageway.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3.828.617 Dated Auqust 13, 1974 Inventor) Louis H. LeBlanc It is certified that error appears in the above-identified patent and that said Letters-Patent are hereby corrected as shown below:

Column 5, line 54 after "second" delete "members" and substitute means Signed and sealed this 29th day of April i975." u

(SEAL) Attest: v C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks 

1. A rifle bar rotation mechanism for a rock drill comprising: an axially extending elongated body member; an axially extending bore in said body member; an elongated rifle bar having a longitudinally extending bore therethrough and having one end portion thereof rotatably mounted within said body member bore; first means received within said body member bore and cooperable with second means on said one end portion for selectively controlling the rotation of said rifle bar; a hollow cam member rotatably coaxially received within said body member bore; said cam member having a peripheral camming surface thereof for controlling the cooperation of said first and second members; first rotative means being in radial driving engagement with said cam member and adapted to be responsive to pressure fluid supplied thereto to rotate said cam member coaxially with respect to the longitudinal axis of said bore; second rotative means having a portion thereof coaxially aligned with said cam member and in driving engagement therewith; and having at least another portion thereof located externally of said body member and being manually operable to rotate said cam member coaxially with respect to the longitudinal axis of said bore; and said first and second rotative means being selectively operable independently of each other.
 2. A rifle bar rotation mechanism as specified in claim 1 wherein said body member includes a back head element having therein a rearward portion of said body member bore and said cam member is received within said rearward portion.
 3. A rifle bar rotation mechanism as specified in claim 2 wherein said first means comprises a plurality of pawl elements pivotally mounted within said body member bore forwardly of said back head, and said second means comprises ratchet teeth on a head element forming said one end portion of said rifle bar.
 4. A rifle bar rotation mechanism as specified in claim 3 wherein said pawl elements are tangentially engagable with said ratchet teeth, some of said pawl elements thus engagable to prevent rotation of said rifle bar in one direction of rotation and at least one other of said pawl elements thus engagable to prevent rotation of said rifle bar in the opposite direction.
 5. A rifle bar rotation mechanism as specified in claim 2 wherein said back head has a cross bore therein peripherally intersecting said rearward portion of said body bore and said first rotative means comprises a double acting piston slidably received in said cross bore and engaging said cam member.
 6. A rifle bar rotation mechanism as specified in claim 5 wherein end portions of said cross bore are adapted to be in communication with a source of pressure fluid.
 7. A rifle bar rotation mechanism as specified in claim 6 wherein said communication of one of said cross bore end portions with a source of pressure fluid is simultaneous with communication of the other of said cross bore end portions with the ambient atmosphere.
 8. A rifle bar rotation mechanism as specified in claim 2 wherein said backhead is provided with a passageway providing said adaptation for communication of said interior of said back head with such a source of pressure fluid.
 9. A rifle bar rotation mechanism as specified in claim 8 wherein a blow tube is slidably received in said rifle bar bore to provide communication of said cam member interior through said rifle bar bore.
 10. A rifle bar rotation mechanism as specified in claim 9 wherein said cam member interior is a through bore therein sealingly receiviNg a head portion of said blow tube and having a side opening communicating with said back head passageway. 